Corrosion is a natural process that occurs when metals react with the environment, leading to their deterioration. It is a common problem in industries, infrastructure, and everyday objects made of metal. Understanding the factors that affect the rate of corrosion is crucial in preventing and mitigating its effects.

Strains in metals affect the rate of corrosion:

- Metals are often subjected to mechanical stresses and strains in various applications. These strains can arise from processes such as bending, stretching, or vibrations. Strains can cause localized changes in the metal's structure, leading to the formation of dislocations and defects.
- These defects provide sites for corrosion initiation, as they create regions of increased reactivity. The strain-induced defects can act as preferential sites for the adsorption of corrosive species, such as oxygen or moisture, leading to accelerated corrosion rates.
- Additionally, strains can also affect the diffusion of corrosive species within the metal. Strain gradients can alter the transport properties, making it easier for corrosive species to penetrate into the metal and reach susceptible regions.
- The combination of strain-induced defects and altered transport properties can significantly increase the rate of corrosion. It is particularly evident in situations where the metal is exposed to cyclic loading or alternating stresses, which can lead to fatigue corrosion.

Other factors affecting the rate of corrosion:

- The reactivity of the metal: Corrosion depends on the reactivity of the metal. More reactive metals, such as iron, are more prone to corrosion compared to less reactive metals like gold or platinum.
- Presence of impurities: Impurities in metals can affect the rate of corrosion. For example, the presence of certain alloying elements can enhance the corrosion resistance of a metal, while other impurities can promote corrosion.
- Presence of electrolytes: Electrolytes, such as salts or acids, can significantly increase the rate of corrosion. They facilitate the flow of ions, allowing for faster electrochemical reactions to occur at the metal surface.

In conclusion, the statement that strains in metals affect the rate of corrosion is true. Strains can induce defects and alter transport properties, leading to accelerated corrosion rates. However, the other statements in the options given are incorrect. The reactivity of the metal, presence of impurities, and electrolytes all have significant effects on the rate of corrosion.